Memory Speed

In this article it's important to remember that in earlier systems running Windows 98 or ME for example, there is a point where the system no longer uses the memory. If your running Win98 and have 64 megs or more of physical RAM, you'll want to open the C:\Windows\System\System.ini file (it opens in notepad) and under the [386Enh] section, enter: "ConservativeSwapfileUsage=1" (without the quotes) to prevent the system from using that slower swapfile before it uses the faster available RAM. You may also under that section add "DMABufferSize=64" without quotations.

When purchasing memory, you'll likely find a plethora of terms with each product. One of the more obvious is the speed rating. Let's assume you go to buy RAM and find the following:
128 MB PC100 - $44
128 MB PC133 - $59
128 MB PC150 - $69

If you buy the more expensive RAM, are you getting a faster memory stick? Will the memory last longer? Will your PC be faster? It depends on the system entirely. More importantly the FSB or Front Side Bus. Having PC133 memory on a motherboard with a 100MHz FSB will result in you having the exact same speed as before. Conversely as the memory can function both ways this lends itself to future upgrades. So, you buy the best with intentions of upgrading the system board. Good choice either way. Systems lately have come with various newer types of memory that need to be placed in a compatible board in a certain configuration (bridged and terminated). You should check your computers manuals for this configuration.

So how does PC100 memory differ from PC133 memory? PC100 memory is essentially "stable" on 100 MHz bus speeds and below. That isn't to say it won't work at 133 MHz and beyond, but it will probably lead to some problems, such as system crashes. PC133 is good for up to 133 MHz bus speeds (by spec). Again, it could reach 150 MHz, but if you're going to use a higher bus speed you might as well buy the higher spec'd memory. To find out which bus speed your system uses, read the manual as this almost always gives the specs of your system.

CAS Latency
You've probably seen memory that says "CAS2" and "CAS3", but you might have no idea what the differences are between the two. We should mention that if your memory doesn't have a specified "CAS" setting listed, it is probably CAS3. CAS3 is cheaper to produce and for the most part, easier to sell. CAS2 is for high-performance applications. What does it all mean?

If your system has CAS2 memory and it is enabled in the BIOS setup, you'll have a very nice speed increase when doing input/output through the RAM. Any program you run uses the system RAM, so in essence, every program is faster. The speed notice may not be visible to the human eye, but it's definitely there. RAM is already so fast compared to a hard drive that when things are loaded from RAM, they seem almost instant. CAS2 makes that instant into 2/3 of an instant. It is significantly faster than CAS3, but you probably won't notice the difference in real-world applications. Also, note that higher bus speeds benefit more from CAS2 than lower bus speeds. The difference between CAS2 and CAS3 may not be as obvious at 100 MHz FSB than it is at 133 MHz FSB and beyond.

In your BIOS configuration ( By hitting DELETE or F12 on boot), there should be an option for adjustable RAM timings. If the option is available, your system can take advantage of CAS2 RAM. If you don't have the option at all, don't bother buying CAS2 unless it's the same price (or close to the same price) of CAS3, because you won't be able to use it with this system. The options usually consist of "CAS Latency", "RAS Precharge Time", and "RAS TO CAS Delay". With CAS2 RAM, you should be able to set all of these to "2".

"ECC" and "Registered" Memory
With ECC (Error control) memory you'll have to take closer look because ECC RAM has extra fault tolerance features that also slow down the RAM. Although it's not a significant slowdown, the extra latency modules should only be used with similar modules to keep stability.

Without them, your system would not be able to detect all of the memory capacity in the system. You can mix and match non-registered and registered modules on certain boards. But again, stick to the same type of modules for stability and compatibility.

Registered modules have extra chips near the connectors on the bottom, making the entire module itself large. These chips help the chipset on your motherboard correctly address the total memory capacity of the memory modules.

Tools Required
No tools are required for installation other than this guide and a phillips screwdriver if you need to remove your case's panels. Do not use screwdrivers removing or placing the memory into their slots!

Safety
Memory sticks or modules are very sensitive to static. ESD, or electro-static discharge, is often released when a person grabs onto something without first grounding themselves. The result of ESD on memory sticks can often and easily lead to instant death for the module. If you work at IBM like I did completing a job on a system without the ESD strap is almost grounds for dismissal!

Consider the following when installing any PC component:
- Don't work in a room with carpeting unless it's absolutely necessary. You should be able to work in the garage or outside or somewhere that doesn't have carpet.
- Before you remove the memory from the anti-static bag and before you begin installation, be sure to ground yourself by touching the computer chassis bare metal. If you leave the computer case plugged in (but turned off) while you work on it, you can be sure the earth ground is intact. If you don't want to ground yourself, get a ground strap
- Make sure you don't drop any components (but don't worry too much I've witnessed parts actually "bounce" off the factory floor and still be 100% usable!)
-If antistatic air (in a can) is available, spray off any dust while working inside your PC

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